If you've been using (or will be using) the uuid and imagick extensions for PHP, you might be able to save yourself a lot of headache by reading this new post from Lars Strojny about his segfault woes.

After trying to trace it down with a backtrace and cachegrind results, he (and Mikko & Pierre) found that both extensions were built against the libuuid.so.1 file. While that wasn't the issue directly, they did find a work-around that helped the issue - renaming some ini files so uuid was loaded first.